The retirement board voted 4-2 to award Lee Partridge the bonus for work last year despite objections to a contract that could pay him more than $4.5 million over about three years.

Trustees Dianne Jacob, a county supervisor, and Dan McAllister, the county treasurer-tax collector, opposed the payout.

For the second consecutive year, the bonus was the most the board could have awarded based on its contract with Partridge in 2009. Much of the incentive was essentially guaranteed because of the performance of the fund.

Partridge was hired to help the retirement system boost performance and efficiency, but the move generated concern among some trustees and retirees. The San Diego County Employees Retirement Association administers retirement benefits to more than 36,000 members.

On Thursday, Trustee David Myers, the board chairman, said he had yet to hear a compelling argument against providing the full bonus. Myers said Partridge exceeded the agreed-upon benchmarks and lowered risk in a challenging environment. Partridge was recently named Small Public Fund Manager of the Year by Institutional Investor magazine.

Since Partridge came on board in October 2009, the fund earned 1.45 percent over the benchmark used by the pension fund and 1.88 percent over the 8.25 percent rate of return set by the board. Both figures were on an annualized basis, said Chief Executive Brian White. Over the same period, Partridge has delivered performance of $241 million over the benchmark and $303 million of over the 8.25 percent annual rate of return, Trustee Douglas Rose said. That helps demonstrate “that the money we paid him was worth it,” Rose said.

“And I will go on the record and say that I will gladly pay the next consultant $3 million over (the first 27 months of the) contract if they can deliver me excess returns of $300 million,” he said.

Responding to criticism that Partridge’s total compensation last year was about six times that of his predecessor’s, Rose said pension board authorizes $60 million to $70 million in management and incentive fees to outside money managers, “which is far in excess of what any county employee gets.”

Partridge’s base pay was $647,700 and he received a $453,390 bonus based on quantitative criteria. The board had discretion over the remaining $194,310.

Jacob noted that Partridge received nearly $1.8 million over the first 15 months of his contract and about $1.3 million over the next year.

“More than $3 million in compensation in less than 2½ years I do not believe can be justified when we are talking about money from a public retirement fund,” Jacob said. “I cannot in good conscience approve additional compensation being considered. I didn’t support the original compensation agreement and I believe it would be inconsistent for me to support what’s before us today.”

She added: “I feel it’s important that my concerns continue to be put on the record and I am being consistent with my past actions.”